Turbine

ABSTRACT

1,029,647. Turbines; centrifugal compressors. SULZER BROS. Ltd. April 6, 1965 [May 11, 1964], No. 14585/65. Headings F1C and F1T.  A radial flow compressor or turbine has a diffuser the axial spacing between the walls 1, 2 of which is adjustable, a ring of stator vanes 5 on wall 1 extending into an annular recess in wall 2, filling elements 6 in the recess shaped to correspond approximately to the flow passages 3 between the vanes and relative to which the vanes slide when the spacing between the walls is adjusted, and sealing members 9 of selflubricating plastic material, such as polytetrafluoroethylene, forming seals between the vanes 5 and the filling elements 6. The sealing members 9 are pressed against the vanes 5 by rubber members 13, members 9, 13 being retained in position by T-pieces 11. Sealing members 9 are also provided between vanes 5 and the outer periphery of the annular recess, Fig. 4 (not shown). Vanes 5 and elements 6 are attached to walls 1, 2 by screws 7, 8 respectively, wall 1 being fixed and wall 2 movable.

Dec. 19, 1967 K. JASSNIKER 3,35

May 10 1965 4 H S 2 V w Dec. 19, 1967 K. JASSNIKER 3,358,965

TURBINE Filed May 10, 1965 2 Sheets-Shei 2 T hm? O7 ATTORNEYS United States Patent 3,358,965 TURBINE Kurt Jassniker, Winterthur, Switzerland, asslgnor to Sulz er Brothers Limited, Winterthur, Switzerland, a SWISS company Filed May 10, 1965, Ser. No. 454,586 Claims priority, application Switzerland, May 11, 1964, 6,088/64 4 Claims. (Cl. 253-40) ABSTRACT OF THE DISCLOSURE There is disclosed a radial diffuser for turbine-type ma chines comprising two coaxial annular diffuser walls axlally movable with respect to each other, a set of stator blades aflixed to one wall and projecting into an annular recess on the other wall, packing or filling members fastened to the other wall and extending between circumferentially adjacent ones of those blades, and sealing members or gaskets affixed to the filling members to engage the surfaces of the blades. Retainers and elastic inserts are provided to hold the gaskets on the filling members and to stress them against the blades in order to obtain a tight seal.

Background of the invention The present invention relates to a turbine having a circular array of stationary guide blades between the walls of a radial difiuser, such walls being axially movable with respect to each other to permit adjustment of the spacing between them. The invention is advantageously employed in turbines of refrigeration plants in which a refrigerant is cyclically compressed and expanded.

In turbines in which a radial diffuser includes stationary blades and in which the diffuser flow cross-section may be varied by displacement of one diffuser wall relative to the other, the guide blades, supported on one wall, must be received in recesses on the other wall to permit the required relative movement of the two walls while retaining the guide action of the blades between them. The shaping and positioning of the recesses in one wall to receive the blades afiixed to the other wall entails substantial manufacturing cost.

It is an object of the invention to reduce the cost of manufacture of such a variable flow cross-section diffuser. In accordance with the invention one difiuser wall, not supporting the blades, is formed on the side thereof adjacent the blades with an annular groove or recess, concentric with the axis of the machine. In this groove are disposed a plurality of packing, filling or spacing members, shaped and positioned to match, at least approximately, the flow spaces between the stationary guide blades of the stator already referred to and which may be supported on the other wall of the diffuser. These members are advantageously provided with self-lubricating sealing members or gaskets, preferably of synthetic plastic material, which slide against the blades and in the gas-flow spaces between adjacent of the blades upon relative movement of the diffuser walls. A similar sealing member, circular in shape, may be provided between the stator blades and the outer periphery of the annular recess.

To achieve a tight seal between these sealing members and the blades, there may be provided elastic stiffening members extending along and near the edges of the sealing members which are to engage the blades, and retainers to press against the sealing members on the side thereof presented to the flow spaces between adjacent blades. For reduction of turbulence and flow losses, the

Patented Dec. 19, 1967 'ice sealing members, stiffening members and retainers are all preferably shaped to present a smooth flat surface to the flow spaces.

Other features of the invention will be disclosed by the following description of an exemplary embodiment, reference being made to the accompanying drawings wherein:

FIG. 1 is a view, in longitudinal section along the axis of a turbine according to the invention, showing part of a bladed radial diffuser;

FIG. 2 is a section along the line IIII of FIG. 1, and

FIGS. 3 and 4 are respectively sections along the lines III-III and IVIV of FIG. 2.

All the drawing show in highly diagrammatic form just those elements which are necessary for an understanding of the invention, like reference characters denoting like elements throughout the drawings.

FIG. 1 shows two annular walls 1 and 2 of a radial diffuser in a turbine, further particulars of which are not shown. Radially, inside these walls the machine includes a rotor (not shown); radially outside thereof the diffuser merges into a volute casing. The space between walls 1 and 2 constitutes a flow chamber 3, the cross-section of which is made variable by the provision for motion, axially of the machine, of the end wall 2, which includes an annular recess 4 into which extends an annular array of stator blades 5. The mechanism for shifting the wall 2 may be of known kind and is not shown in detail. The wall 1 to which stator blades 5 are afiixed is not movable. FIG. 1 shows the flow chamber 3 as having parallel boundary surfaces, but the invention is not limited to a parallel-wall type radial diffuser and also includes diffusers in which the flow channel widens conically outwards, for example.

The stator blades 5 on wall 1 penetrate into the annular cavity 4 of wall 2 to an amount depending on the axial separation of the two walls. As indicated in FIG. 2, filling members 6 are disposed in the recess, and are disposed and dimensioned to accommodate the stator blades '5 between them. The blades 5 and filling members 6 are fastened to the walls 1 and 2 respectively by means of screws 7 and 8 (FIG. 3), and desirably by pins or dowels (not shown) as well, for accuracy of location.

As indicated in FIGS. 3 and 4, the filling members 6 and the limits of the recess 4 on the one hand, and the blades 5 on the other hand are constructed to have substantial clearance between them, so that they can be manufactured with large tolerances and at low cost. In comparable constructions of the prior art on the other hand, hand work was required to fit each blade to its individual recess between adjacent sealing members.

In accordance with the invention therefore, the actual seal between the blades 5 and members 6, and between the blades and the radially outer limit of recess 4 (FIG. 4), is effected by means of gaskets or sealin members 9, preferably self-lubricating in nature and made of suitable synthetic plastic material such as polythene. These sealing members are secured to the filling members 6 and to the wall 2 adjacent the radially outer edge of the recess 4 therein. As indicated in FIGS. 3 and 4, these sealing members 9 are formed with an edge 10 which is pressed against the Hanks and radially outer limits of the blades.

The sealing members are fastened to the members 6 and wall 2 by means of retainers 11 which in turn are screwed or otherwise secured to the members 6 and wall 2. In the case of the members 6, the retainers 11 may be of T-shaped section, so as to hold a sealing member 9 on each of the two circumferentially opposite sides of each filling member 6. The retainers may be provided 3 with fillets or steps 12, engaging corresponding grooves in the sealing members.

A tight seal between the blades and the opposite diffuser wall 2 is important, especially along the spiral length of the blades and sealing members, since the pressure at the exit end of the diffuser is much higher than at the entry end.,This sealing action, provided by the invention in an effective and economical manner, prevents any pressure equalization via the otherwise open spaces between adjacent sealing members 6.

To improve the sealing contact between the blades and sealing members, a resilient intermediate strip 13 is advantageously provided in the groove of the sealing member occupied by the retainer step 12, and outboard of the latter, i.e. adjacent the sealing edge 10 of the sealing member. This groove may have a trapezoidal section, widened to accommodate the strip 13 as Well as the retainer step 12, and when the retainers are drawn down against the filling members 6 and Wall 2 (FIG. 4), the resulting deformation of the elastic strip 13 improves the sealing action.

For low-loss flow of the working substance through the diffuser, the elements 9, 11 and 13 are formed to have a common smooth surface on the side thereof presented to the flow passages between adjacent stator blades, these passages being indicated at 3 in FIG. 3. It is these passages whose axial length (vertical dimension in FIG. 3) is varied by relative axial motion of the walls 1 and 2.

While the invention has been described herein in terms of a presently preferred embodiment thereof, the invention is not limited thereto, but comprises all modifications on and departures therefrom falling within the spirit and scope of the appended claims.

I claim:

1. A turbine-type machine comprising a plurality of stator blades arranged in an annular array, a first diffuser wall to which said blades are afiixed at one axial end of said array, a second diffuser wall adjacent the other axial end of said array, said second Wall having an annular recess therein receiving said blades, one of said walls being movable with respect to the other axially of said array, a plurality of filling members disposed in and fastened to the bottom of said recess, said filler members being disposed each between two circumferentially adjacent ones of said blades and being shaped to approximately correspond to the space between adjacent ones of said blades, and sealing means of self-lubricating plastic material fastened to each of said filling members and engaging the adjacent ones of said blades.

2. A turbine-type machine according to claim 1 wherein said first wall is stationary and said second wall is movable.

3. A turbine-type machine according to claim 1 wherein said sealing means comprise, for each of said filling members, a plurality of sealing members, said machine further comprising, for each of said filling members, a retaining member affixed to such filling member and intermediate members of resilient material engaged by said retaining member and stressing a separate one of said sealing members against the adjacent one of said blades.

4. A turbine-type machine according to claim 3 wherein said sealing members, retaining member and resilient members present a smooth fiat surface between each pair of adjacent ones of said blades.

References Cited UNITED STATES PATENTS 2,996,996 8/1961 Jassniker 103-97 MARTIN P. SCHWADRON, Primary Examiner.

EVERETTE A. POWELL, ]R., Examiner. 

1. A TURBINE-TYPE MACHINE COMPRISING A PLURALITY OF STATOR BLADES ARRANGED IN AN ANNULAR ARRAY, A FIRST DIFFUSER WALL TO WHICH SAID BLADES ARE AFFIXED AT ONE AXIAL END OF SAID ARRAY, A SECOND DIFFUSER WALL ADJACENT THE OTHER AXIAL END OF SAID ARRAY, SAID SECOND WALL HAVING AN ANNULAR RECESS THEREIN RECEIVING SAID BLADES, ONE OF SAID WALLS BEING MOVABLE WITH RESPECT TO THE OTHER AXIALLY OF SAID ARRAY, A PLURALITY OF FILLING MEMBERS DISPOSED IN AND FASTENED TO THE BOTTOM OF SAID RECESS, SAID FILLER MEMBERS BEING DISPOSED EACH BETWEEN TWO CIRCUMFERENTIALLY ADJACENT ONES OF SAID BLADES AND BEING SHAPED TO APPROXIMATELY CORRESPOND TO THE SPACE BETWEEN ADJACENT ONES OF SAID BLADES, AND SEALING MEANS OF SELF-LUBRICATING PLASTIC MATERIAL FASTENED TO EACH OF SAID FILLING MEMBERS AND ENGAGING THE ADJACENT ONES OF SAID BLADES. 